Synthesis and Structural Characterization of Three Unique Helicobacter pylori α-Cholesteryl Phosphatidyl Glucosides

Steryl glycosides produced by bacteria play important biological roles in the evasion and modulation of host immunity. Step‐economical syntheses of three cholesteryl‐6‐O‐phosphatidyl‐α‐D‐glucopyranosides (αCPG) unique to Helicobacter pylori have been achieved. The approach relies upon regioselective deprotection of per‐O‐trimethylsilyl‐α‐D‐cholesterylglucoside at C6 followed by phosphoramidite coupling. Global TMS ether deprotection in the presence of oxygen and subsequent deprotection of the cyano ethyl phosphoester afforded the target compounds in 16–21 % overall yield starting from D‐glucose. The structures of these natural products were determined using a combination of 2D NMR methods and mass spectrometry. These robust synthesis and characterization protocols provide analogues to facilitate glycolipidomic profiling and biological studies. Analogues of α‐cholesteryl phosphoglycolipids (αCPGs), which are immunostimulants produced by H. pylori bacteria, were synthesized in a step‐economical manner. The approach relies upon the regioselective deprotection of per‐O‐trimethylsilyl‐α‐D‐cholesterylglucoside at C6 followed by the phosphorylation with a phosphoramidite. TMS=trimethylsilyl.